In industry there is a business segment which provides electronic devices which yield precise time. Some of these devices derive high precision time through a transfer process whereby they transfer time from a satellite system. One such satellite system is the Global Positioning System (GPS). Various manufacturers use GPS receivers in which precise time is derived from one of the atomic clocks in the satellites (GPS Time Receiver). These are known by various names such as GPS Time Receivers, Time & Frequency Standards, and other names. Sometimes they also provide precise frequency measurement. Such Time Receivers are sold for a variety of applications where precise time is important. In certain applications there is a need to synchronize these Time Receivers with each other. One such application area is the synchronization of telecommunications signals. The synchronization process is handled in a number of conventional ways.
When satellite clocks are required to be instantaneously synchronized with each other at the nanosecond level difficulties arise due to the misapplication or misinterpretation of the relativistic effects and gravity effects between a moving clock in a satellite and a stationary Time Receiver on the ground. This invention is a new and nontraditional method for performing a synchronization process that enables instantaneous synchronization of such Time Receivers (clocks) to a high level of precision. One use of this invention could be to modify an existing clock to perform the synchronization process defined in this patent application.
As refered to above, the problem addressed in this disclosure is the instantaneous synchronization of two or more clocks located at different positions in a given spatial coordinate system, by means of either two-way or one-way radio communication between clocks. Generally, some or all of the clocks will be in motion relative to that coordinate system. In a typical application the coordinate system is attached to the earth, and some of the clocks would be on the surface of the earth, while others would be in satellites orbiting the earth. The satellite clocks would typically be atomic (Rubidium or Cesium), and the earthbound clocks might be either crystal oscillator or atomic.
When some of the clocks are in moving satellites, in one aspect of the invention synchronization requires that relativistic effects be taken into account.
Einstein's theory of Special Relativity is based on two postulates. The first is commonly called the relativity postulate, which states that for any two inertial frames in uniform relative motion, the laws of physics within each frame are identical. The second postulate is that the speed of light is constant, regardless of the inertial frame in which it is measured.
Einstein showed that if both postulates are assumed, that neither time nor distance is absolute. Specifically, if measurements of the time interval and/or distance between two events in space-time are made within each of two inertial frames in relative motion, the measurements will differ.
The non-absolute nature of time posited by the Special Theory of Relativity poses complications in the process of time synchronization, and has led to errors resulting from misapplication of the Special Theory.
The invention described herein removes the complications imposed by the Special Theory, by assuming only the first of Einstein's two postulates to produce a space-time theory in which time can be regarded as absolute. As a consequence, distance and velocity are defined somewhat differently, but the process of time synchronization is made extremely simple.